package Demo1;

public class Computer {

    public void powerOn(){
        System.out.println("打开电脑...");
    }

    public void powerOff(){
        System.out.println("关闭电脑...");
    }

    public void useDevice(USB usb){
        usb.openDevice();
        if(usb instanceof Mouse){
            Mouse mouse = (Mouse) usb;
            mouse.click();
        }else if(usb instanceof Keyboard){
            Keyboard keyboard = (Keyboard)usb;
            keyboard.input();
        }
        usb.closeDevice();
    }

}
